Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[144] Now when the king saw that the walls of Jerusalem stood in need of being better secured, and made stronger, (for he thought the wails that encompassed Jerusalem ought to correspond to the dignity of the city,) he both repaired them, and made them higher, with great towers upon them; he also built cities which might be counted among the strongest, Hazor and Megiddo, and the third Gezer, which had indeed belonged to the Philistines; but Pharaoh, the king of Egypt, had made an expedition against it, and besieged it, and taken it by force; and when he had slain all its inhabitants, he utterly overthrew it, and gave it as a present to his daughter, who had been married to Solomon; for which reason the king rebuilt it, as a city that was naturally strong, and might be useful in wars, and the mutations of affairs that sometimes happen. Moreover, he built two other cities not far from it, Beth-horon was the name of one of them, and Baalath of the other. He also built other cities that lay conveniently for these, in order to the enjoyment of pleasures and delicacies in them, such as were naturally of a good temperature of the air, and agreeable for fruits ripe in their proper seasons, and well watered with springs. Nay, Solomon went as far as the desert above Syria, and possessed himself of it, and built there a very great city, which was distant two days' journey from Upper Syria, and one day's journey from Euphrates, and six long days' journey from Babylon the Great. Now the reason why this city lay so remote from the parts of Syria that are inhabited is this, that below there is no water to be had, and that it is in that place only that there are springs and pits of water. When he had therefore built this city, and encompassed it with very strong walls, he gave it the name of Tadmor, and that is the name it is still called by at this day among the Syrians, but the Greeks name it Palmyra.